I recommand a softbox,instead of an umbrella. Much better light for most aplications.
Well you need a flash & a wireless radio trigger. The flash could be a 430EX or 580EX,if you want to get a Canon flash,but the radio trigger doesn't have to be expensive. I have 60$ Hahnel trigger & it works great & it has a working distance of max. 100 metres.

As for DIY,I made a softbox & it's producing light at the same quality as the pro models (because the principles & materials are about the same). Search on youtube & google for DIY softboxes,you'll be amazed on how many results you can find. Still,if you have the money,buy a pro one,DIY softboxes have their disadvantages.

Just remember that the size of your light source makes a difference when shooting more than one subject at once. For instance, if your shooting a large family portrait, you will need a large soft box say a 50 inch or a large umbrella such as a 60 inch convertible. Otherwise you will need to get into multiple flash units and triggers to light these situations. For a single person portrait a medium soft box or umbrella on a light stand will do the trick in most cases. I personally use a 60' umbrella with one light at the moment. It does give me a lot of possibilities but doesn't work in every situation. 60" umbrella = $35 at B&H photo

Do not discount the power of a good window. Learn how to work with ambient light. Place a subject in front of the window, use some white panels around her face to reflect light (skin is also reflective) and you will be amazed at the results you can get.

If you really want to get strobes, I suggest one monolight head from www.alienbees.com and a large softbox or a large umbrella as already suggested.

A sost box gives you a smaller grey area between light and shadow than an umbrella
So choose according to your taste and need.
Don't forget gels for the flash. If you shoot indoors and have daylight from windows you don't need gels. But if you have artificial light you have to put filters on the flash otherwise you'll have big problems in post production.

You really need 2 lights. One for the subject and another for the background or as a fill etc.

There are several ways of triggering flashWired (with a cable, using ports and various adaptors)
Infra Red (this is usually built into the flashguns, but not always the camera)
Radio/Wireless (using an external kit)
Slave (the flash detects the other flashes and triggers)

If you wanted to go down the radio route, then you can either buy an expensive system or a cheaper one from ebay.

With regards to using diffusers etc, well that would depend on your needs and what works best for you.

Also of mention is a ring-light where you have virtually no shadows with only one light. Though they leave a hideous unnatural catchlight... in my opinion anyway.

You have a lovely site digitalfrog and a strong portfolio, though I feel out of consideration for other form members you should have a nsfw (not safe for work) warning near your link. Even though all your nudes are done in a pleasing and tasteful manner.

@hello people

I would recommend you play around with natural light before diving into the world of flash. A few helpful items would be a large diffusion panel and silver/white reflectors. Flash can be an expensive venture and you should do a large amount of research before investing in any particular equipment.

Though if you feel you're ready I would recommend alien bee's when starting out. They are more powerful, cheaper and produce a better quality of lights than the canon speedlights are capable of. Check out: www.alienbees.com

As others have said, it's a good idea to experiment with natural light first. Then when you feel comfortable or curious to take the next step (which is only natural for an enthusiastic photographer!), dive into the world of wireless flash. The 60D is a great camera to get started in portrait/flash photography. First of all, you've got a built-in wireless transmitter that'll trigger your Canon flashes. If you don't have Canon flashes or you're using a strobe, then you'll of course need some triggers (such as these: http://www.aputure.com/blog/?p=1774).

I'd suggest starting out with the basics: a few speed llghts, umbrellas, reflectors, and light stands. Then if you crave more, step up with some studio strobes, softboxes, beauty dishes, and so on.

And then also i need to know.How powerfull does the strobe need to be? (i.e. 200 watts? 300 500?)How big does the softbox need to be, it was my understanding that the bigger the softbox the softer the light so a big box seems better then a small one, or is this not the case? (i.e. hairlight needs to be smaller? to prevent shadows).

I am totally new to all this stuff but i have seen some kelby training videos and it looked not very complicated at all to set it up.Especially with strobe and softboxes it is basically what you see is what you get according to the instructor.

I know this topic is old but i did not want to open a new topic since you guys probabaly gonna refer me to this topic anyway.